1. Field of the Invention
This invention relates to illumination equipment for inducing alpha rhythms in human brain waves.
2. Description of the Prior Art
It has been long known that many alpha rhythms are observed in brain waves under an exposure of 12 Hz intermittent flash lights. The alpha rhythms are usually observed in brain waves of a person when he is settling himself down with his eyes closed or relaxing and the stimuli from the flash lights trigger an entrainment of the alpha rhythms. This is described in "Dynamic Performance of Alpha Waves When A Person Is Settled Down or under An Exposure of Flash Lights" by Kouhei Harada et al., Vol. 108 No. 2, Journal of Society of Electrical Engineers which is herein incorporated by reference for its teachings in the field of alpha waves. However, it is said according to the experiences acquired in lighting that an unpleasant flickering impression occurs under the monotonous intermittent flash lighting at around this frequency of 12 Hz.
Also, as a method to induce a person to relaxation by an exposure to intermittent lighting, a goggle like apparatus equipped with a light source capable of emitting a high level of illumination has been in use. The goggle like apparatus is worn by the person in the same manner as a skiing goggle is worn and flash lights of a high illuminating power are shed on the closed eyes intermittently. This method is more fully described in "Learning Relaxation Device" Gorges, D. E. U.S. Pat. No. 4,315,502.
However, a goggle like apparatus is required and the eyes are desirably closed when this method is employed. Further, such performance problems as fluctuations in intermittent flashing, etc. are not even hinted at all in this document.